<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>填充颜色</title>
</head>
<body>
<canvas id="canvas" width="500" height="800"></canvas>
<script>
  function draw() {
    var ctx = document.getElementById('canvas').getContext('2d');
    ctx.fillRect(0,0,300,300);
    for (var i=0;i<3;i++) {
      for (var j=0;j<3;j++) {
        // 保存上一个
        ctx.save();
        // 重新设置样式
        ctx.strokeStyle = "#9CFF00";
        // 移动到当前原点
        ctx.translate(50+j*100,50+i*100);
        // 绘制图形
        drawSpirograph(ctx, 20*(j+2)/(j+1), -8*(i+3)/(i+1), 10);
        // 恢复上一个的样式
        ctx.restore();
      }
    }
  }
  function drawSpirograph(ctx,R,r,O){
    var x1 = R-O;
    var y1 = 0;
    var i  = 1;
    ctx.beginPath();
    ctx.moveTo(x1,y1);
    do {
      if (i>20000) break;
      var x2 = (R+r)*Math.cos(i*Math.PI/72) - (r+O)*Math.cos(((R+r)/r)*(i*Math.PI/72))
      var y2 = (R+r)*Math.sin(i*Math.PI/72) - (r+O)*Math.sin(((R+r)/r)*(i*Math.PI/72))
      ctx.lineTo(x2,y2);
      x1 = x2;
      y1 = y2;
      i++;
    } while (x2 != R-O && y2 != 0 );
    ctx.stroke();
  }
  draw()
</script>
</body>
</html>